Alzheimer's disease is a disease characterized by degeneration and loss of neurons and also by the formation of senile plaques and neurofibrillary change. Presently, treatment of Alzheimer's disease is limited to symptomatic therapies with a symptom-improving agent represented by an acetylcholinesterase inhibitor, and the basic remedy which prevents progress of the disease has not been developed. A method of controlling the cause of onset of pathologic conditions needs to be developed for creation of the basic remedy of Alzheimer's disease.
Aβ protein, which is a metabolite of amyloid precursor protein (hereinafter referred to as APP), is considered to be greatly involved in degeneration and loss of neurons as well as onset of demential conditions (for example, see Klein W L, et al Proceeding National Academy of Science USA, Sep. 2, 2003, 100(18), p. 10417-22), suggesting a molecular basis for reversible memory loss.
Nitsch R M, and 16 others, Antibodies against β-amyloid slow cognitive decline in Alzheimer's disease, Neuron, May 22, 2003, 38(4), p. 547-554) suggest that the main components of Aβ protein are Aβ40 consisting of 40 amino acids and Aβ42 having two additional amino acids at the C-terminal. The Aβ40 and Aβ42 tend to aggregate (for example, see Jarrell J T et al, The carboxy terminus of the β amyloid protein is critical for the seeding of amyloid formation: implications for the pathogenesis of Alzheimer's disease, Biochemistry, May 11, 1993, 32(18), p. 4693-4697) and constitute the main components of senile plaques (for example, (Glenner G G, et al, Alzheimer's disease: initial report of the purification and characterization of a novel cerebrovascular amyloid protein, Biochemical and Biophysical Research Communications, May 16, 1984, 120(3), p. 885-90. See also Masters C L, et al, Amyloid plaque core protein in Alzheimer's disease and Down's syndrome, Proceeding National Academy of Science USA, June 1985, 82(12), p. 4245-4249.).
Furthermore, it is known that mutations of APP and presenelin genes, which are observed in familial Alzheimer's disease, increase production of Aβ40 and Aβ42 (for example, see Gouras G K, et al, Intraneuronal Aβ142 accumulation in human brain, American Journal of Pathology, January 2000, 156(1), p. 15-20. Also, see Scheuner D, et al, Nature Medicine, August 1996, 2(8), p. 864-870; and Forman M S, et al, Differential effects of the Swedish mutant amyloid precursor protein on β-amyloid accumulation and secretion in neurons and nonneuronal cells, Journal of Biological Chemistry, Dec. 19, 1997, 272(51), p. 32247-32253.). Therefore, compounds which reduce production of Aβ40 and Aβ42 are expected to be agents for controlling progress of Alzheimer's disease or for preventing the disease.
These Aβs are produced when APP is cleaved by beta secretase and subsequently cleaved by gamma secretase. In consideration of this, creation of inhibitors of γ-secretase and β-secretase has been attempted for the purpose of reducing production of Aβs. Many of these known secretase inhibitors are peptides or peptidomimetics such as L-685,458. L-685,458, an aspartyl protease transition state mimic, is a potent inhibitor of γ-secretase activity (Biochemistry, Aug. 1, 2000, 39(30), p. 8698-8704).
There is a need for new compounds, formulations, treatments and therapies to treat diseases and disorders associated with Aβ. It is, therefore, an object of this invention to provide compounds useful in the treatment or prevention or amelioration of such diseases and disorders.